Facile optical assemblies and components

ABSTRACT

A micro identification system supports facile optical assemblies and components. A segment of optical fiber can comprise an identifier formed via actinic radiation. The identifier can generate a laser interference pattern that can be read through a cylindrical surface of the optical fiber to determine a code. Modified optical fibers are those fibers that have been shaped or coated to an extent beyond the demands of normal communications optical fibers. In one example, modified fibers are no longer than about two feet in length. For another example, the modified fibers can have either a non-cylindrical end face, a non flat end face, an end face the plane of which is not perpendicular to the longitudinal axis of the waveguide, an end face coated with high density filter, or an identifier on or near an end face.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of and claims priority to U.S.Non-Provisional patent application Ser. No. 11/980,337, entitled “FacileOptical Assemblies and Components” and filed Oct. 30, 2007 in the nameof Wach et al., now U.S. Pat. No. 8,135,250, which is a continuation ofand claims priority to U.S. Non-Provisional patent application Ser. No.10/429,166, entitled “Facile Production of Optical CommunicationAssemblies and Components” and filed on May 2, 2003 in the name of Wachet al., now U.S. Pat. No. 7,298,936, which is a continuation of andclaims priority to U.S. Non-Provisional patent application Ser. No.10/010,854, entitled “Facile Production of Optical CommunicationAssemblies and Components” and filed on Dec. 4, 2001 in the name of Wachet al., now abandoned which claims priority under 35 U.S.C. 119 to thefiling date of Dec. 4, 2000 accorded to the U.S. Provisional PatentApplication Ser. No. 60/251,270. The entire contents of U.S.Non-Provisional patent application Ser. No. 11/980,337; U.S.Non-Provisional patent application Ser. No. 10/429,166; and U.S.Non-Provisional patent application Ser. No. 10/010,854 are herebyincorporated herein by reference.

BACKGROUND OF THE INVENTION

Fiber to fiber and fiber to waveguide linking devices that have beendescribed in the art tend to focus on a substantial length of fiberplaced for linkage to another fiber or to a planar waveguide. Prior artconnectors and splicing devices typically do not meet the increaseddemand for minimizing on-line manufacturing time or partreplacement/repair time to meet the overall cost requirements foroptical communications equipment, particularly in high volume productionoperations. With the tremendous need for increasing bandwidth, a needexists in the art for increased precision in such linkages and formodifying or eliminating rate-limiting steps in component manufacturing.The increase in overall demand for high quality optical components atmodest cost has intensified the importance of achieving high qualityconsistently and efficiently.

Fiber modification techniques disclosed in U.S. Pat. No. 5,953,477,entitled “Method and Apparatus for Improved Fiber Optic LightManagement,” filed Mar. 13, 1997, address these challenges. However, theincreased capability of separating wavelengths made possible by theseadvances has further increased the need for precision in other aspectsof manufacturing optical assemblies. Cirrex U.S. patent application Ser.No. 09/318,451, entitled, “Optical Assembly with High PerformanceFilter,” filed May 25, 1999, (incorporated herein by reference in itsentirety), which has now issued as U.S. Pat. No. 6,404,953, describesvarious modifications to fibers. Content of U.S. patent application Ser.No. 09/318,451 has been inserted below under the heading “From U.S.patent application Ser. No. 09/318,451 Entitled “Optical Assembly withHigh Performance Filter”” with FIGS. 1, 2, 3, 4, 5, 6 7, 8, 9, 10, 11a,and 11b respectively renumbered as FIGS. 8, 9, 10, 11, 12, 13, 14, 15,16, 17, 18 a, and 18 b and the letter “x” appended to the figurereference numbers to avoid confusion with other disclosed figures andfigure reference numbers. Cirrex U.S. Patent Application Ser. No.60/213,983 entitled, “Micro Identifier System and Components for OpticalAssemblies,” filed Jun. 24, 2000 (also incorporated herein by referencein its entirety) describes a system having an identifying mechanism forhigh performance waveguides that is machine-readable (especially, byoptical means, for example, using a laser interference pattern) forquick and accurate recall of information included in the identifyingmechanism. Content of U.S. Patent Application Ser. No. 60/213,983 hasbeen inserted below under the heading “From U.S. Patent Application No.60/213,983 Entitled “Micro Identifier System and Components for OpticalAssemblies” with FIGS. 1, 2, 2a, 3, 4, and 5 respectively renumbered asFIGS. 19, 20, 20 a, 21, 22, and 23 and the letter “y” appended to thefigure reference numbers to avoid confusion with other disclosed figuresand figure reference numbers. Many of the individual components of suchoptical assemblies are extremely small and technically complex.Differences between component assembly pieces or even differences withinindividual pieces are difficult to discern. The '983 patent applicationdescribes how etching or engraving, for example, of a cladding surfacecan provide precise and detailed product information, including: themanufacturer, the core and cladding dimensions, compositions, indices ofrefraction, and other imprinting. Internal identifiers of that type canalso be utilized for system integrity/uniformity checks for qualityassurance.

Additional details may be important for other types of optical fibers.For example, the end face of one fiber may be intentionally angled sothat its face is not uniformly perpendicular to its axis and the axis ofa waveguide with which it is to be mated. (See Cirrex U.S. patentapplication Ser. No. 09/578,777, entitled, “Method and System forIncreasing a Number of Information Channels Carried by OpticalWaveguides,” which is incorporated herein in its entirety by referenceand which has now issued as U.S. Pat. No. 6,542,660.) For a very slightangle, it may be critical to have the end face precisely oriented as itmates with the waveguide. The extent to which the fiber core isoff-center or elliptical may also be included in the identifier. Theidentifier on the fiber and the waveguide provides sufficientinformation for the mating to be precise.

One advantage of using the peripheral surface of a fiber end face forthe identifier is relative space availability. The entire periphery ofthe end face could be utilized if information space and image clarityare required. Similarly, the probability of that area causing fiberfunction limitations is low and could be reduced further, for example,by covering disrupted (etched/engraved) surface areas with material thatwould restore transparency to wavelengths negatively affected withoutdetrimentally affecting the readability of the image. Such factors playa role in determining which identifier process, marking and location toutilize. It also may be critical to high volume production for theinformation to be read significantly in advance of the mating operationand in some cases even by a different manufacturer. Each improvement inone area exposes additional challenges for the manufacturing processesin other areas, for example, in assuring appropriate, precise fiber tofiber, or fiber to waveguide mating.

SUMMARY

In accordance with the present invention, a modified fiber interlink,typically an optical assembly multi-channel subcomponent, can be createdto form the optical link between multiple channel waveguides to bemated. For example, modified fiber interlinks form optical paths betweenmultiple fibers and a multi-channel planar waveguide. Modified opticalfibers are those that have been shaped or coated to an extent beyond thedemands of normal communications optical fibers. In one example,modified fibers are no longer than about two feet in length and can haveeither a non-cylindrical end face, a non-flat end face, an end face theplane of which is not perpendicular to the longitudinal axis of thewaveguide, an end face coated with high density filter, or an identifieron or near an end face. In another example, the modified fiber caninclude at least one high density filter in the interlink within aninterlink channel.

Modified fiber interlinks can be manufactured in a separate operationand thus taken off-line from the main optical assembly manufacturingline. These integral interlinks, in which fibers have been shaped soprecisely and/or coated with special filters, can be included in opticalassemblies to ultimately provide their beneficial functions withoutslowing the entire assembly operation. This off-line production canresult in a subcomponent that minimizes linkage time in the fullcomponent assembly operation. The subcomponent also can decrease thepotential for defective linkages or less than optimal performance inboth the subcomponent manufacturing operation and the assemblyoperation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts in exaggerated perspective an interlink having fourdifferently configured waveguides in accordance with an exemplaryembodiment of the present invention.

FIG. 2 shows the exemplary interlink of FIG. 1 in cutaway along the AAplane.

FIG. 3 depicts in exaggerated perspective a planar waveguide configuredfor mating with the exemplary interlink of FIG. 1.

FIG. 3 a illustrates in exaggerated perspective a planar waveguide facehaving a groove surrounding each port for mating with a matingprojection surrounding each mating port on a modified fiber interlink inaccordance with an exemplary embodiment of the present invention.

FIG. 3 b illustrates a mating projection and a groove for a planarwaveguide interlink interface in accordance with an exemplary embodimentof the present invention.

FIG. 4 depicts in cutaway an interlink with cylindrical fibers with highdensity filters on fiber ends in accordance with an exemplary embodimentof the present invention.

FIG. 5 illustrates a fiber of FIG. 4 having an identifier embeddedthereon in accordance with an exemplary embodiment of the presentinvention.

FIG. 6 illustrates in schematic two interlinks used in an add-dropmultiplexer application in accordance with an exemplary embodiment ofthe present invention.

FIG. 7 illustrates in cutaway additional configurations of waveguides ininterlink applications in accordance with an exemplary embodiment of thepresent invention.

FIG. 8 is a perspective of an optical assembly end portion illustratinga masked, filtered fiber end, from U.S. patent application Ser. No.09/318,451.

FIG. 9 is a cross sectional magnified view of an optical assembly inaccordance with FIG. 8 with exaggerated fiber core, filter, and maskthickness dimensions, from U.S. patent application Ser. No. 09/318,451.

FIG. 10 is an end view of an optical assembly illustrating a mask havinga hexagonal exterior profile and a circular aperture, from U.S. patentapplication Ser. No. 09/318,451.

FIG. 11 is a distorted perspective of an uncompleted optical assemblyend portion illustrating a mask precursor having a hexagonal profile,from U.S. patent application Ser. No. 09/318,451.

FIG. 12 is an end view of a cluster of uncompleted optical assembliesend portions, from U.S. patent application Ser. No. 09/318,451.

FIG. 13 is a perspective of two optical assemblies with masks placed inmask end near mask end configuration illustrating mating orientation,from U.S. patent application Ser. No. 09/318,451.

FIG. 14 is a perspective of two optical assemblies in mask end to maskend, mating connection, from U.S. patent application Ser. No.09/318,451.

FIG. 15 is a cross sectional view illustrating two optical assemblieseach having beveled end faces with mask end near mask end configurationillustrating mating orientation, with exaggerated fiber core, filter,and mask thickness dimensions, from U.S. patent application Ser. No.09/318,451.

FIG. 16 is a cross sectional view illustrating two optical assembliesoriented for end to end splice using a connection device mated to themasked assembly ends, from U.S. patent application Ser. No. 09/318,451.

FIG. 17 is a cross sectional view illustrating two optical assembliesoriented for end to end splice using a connection device having a fluidentry/evacuation port, from U.S. patent application Ser. No. 09/318,451.

FIG. 18 includes 18a, which is an end view of a splice connection deviceas in FIG. 17 and including a channel for aligning the fiber end faces,and 18 b, which is a blow-up of the channel and its surrounds, from U.S.patent application Ser. No. 09/318,451.

FIG. 19, from U.S. Patent Application No. 60/213,983, illustratesseveral embodiments of an identifier means.

FIG. 20, from U.S. Patent Application No. 60/213,983, shows inperspective view a system that includes a reading means for sufficientidentification to initiate appropriate reaction.

FIG. 20 a, from U.S. Patent Application No. 60/213,983, illustrates inend view cutaway a drive having rollers supporting a fiber segment.

FIG. 21, from U.S. Patent Application No. 60/213,983, illustrates inperspective view several options for placement or configuration ofidentifier spaces.

FIG. 22, from U.S. Patent Application No. 60/213,983, illustrates afiber having a core and a cladding.

FIG. 23, from U.S. Patent Application No. 60/213,983, illustratespurposefully created index of refraction disruptions in cladding of afiber.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

As shown by the exemplary embodiment in FIG. 1, interlink 4 links byproviding optical channels, waveguides 5, 6 (an optical fiber formed byfusing fiber segment 6 a to fiber segment 6 b forming junction 12 a) 8,and 9, between a planar waveguide (see planar waveguide unit 30 in FIG.3) and at least one optical fiber system 10 of which optical fiber 19 fis a part. Optical fiber 19 f can be mated to waveguide 9, preferably anoptical fiber, at interface 17, by inserting fiber 19 f in channel orrecess 4 c of block 4 a (See FIG. 2 for additional detail). For example,by using an appropriate epoxy, fiber 19 f can be fused to fiber 9 with afilter disposed at the interface 17 therebetween. Optical fiber 18 f canbe mated to waveguide 8 at interface 18 by inserting fiber 18 f into alocking mechanism 22 such as an optical seal housing. The lockingmechanism 22 is coupled to face 2 of the interlink 4 by flanges 21 thatengage the locking mechanism 22. Disposed at interface 18 can be afilter. Overall, waveguides 5, 6, 8, and 9 of interlink 4 demonstratevarious types of optical connections that can exist within interlink 4.It will be understood that the present invention is not limited to thenumber and types of waveguides shown within interlink 4. For example,FIG. 7 illustrates yet another exemplary embodiment of the type ofwaveguide, configuration that can be disposed within an interlink 4.

Block 4 a is rigid, constructed of material opaque to the wavelengths oflight expected to be transmitted through the embedded waveguides andlight to which the unit is exposed. The material is preferably a plasticthat is resistant to thermal expansion and is thermally stable. Fibers15 f, 16 f, 18 f of the optical fiber system can mate with waveguideends 15, 16, and 18 respectively of interlink 4. Multi-channel planaroptical waveguide unit 30 (see FIG. 3) has a docking surface 39 andports 31, 32, 33′ and 34 optically open to waveguide channels of planaroptical waveguide unit 30 which ultimately communicate with waveguides35 a, 35 b, 35 c and 35 d. Face surface region 1 of interlink 4 (FIG. 1)and its positioning pins 7 a, 7 b, 7 c, 7 d and 7 e mate with dockingsurface 39 (FIG. 3) and its pin receptacles 37 a, 37 b, 37 c, 37 d, and37 e, respectively. Ports 11, 12, 13 and 14 of interlink 4 (FIG. 1) mateprecisely with ports 31, 32, 33 and 34 respectively (FIG. 3) of planaroptical waveguide unit 30. Secure mating for each of the respectivewaveguide ends can be accomplished by using an appropriate epoxy orother material (e.g. index matching gel) to assure transparentconnection. For less than permanent connection, the mating could also besecured by using an index matching gel and a connection system thatsecurely but releasably connects (e.g. using latches) interlink 4 facesurface 1 with the docking surface 39 of planar waveguide unit 30.Another alternative that could be used in lieu of or with placement pinsand receptacles is a male/female grooving system, as shown inexaggerated perspective in FIG. 3 b.

FIG. 3 a shows a multi-channel planar waveguide face (docking surface)36 having groove 36 g spaced and completely but separately surroundingeach of the ports, 31 a, 32 a, 33 a and 34 a. A mating modified fiberinterlink would include a precisely dimensioned face surface havingshaped, continuous projections 26 p that would mate with groove 36 g, asillustrated in FIG. 3 b. The interlink would also include ports thatwould mate precisely with ports 31 a, 32 a, 33 a and 34 a. As best shownin FIG. 3 b, mating projection 26 p mates exactly with groove 36 g, butthe projection could be modified to guide itself to the full depth ofgroove 36 g. The advantage of a grooving system is that it helps toassure no unintended photon transfer between non mated ports.

In FIG. 1, modified fiber interlink 4 includes optical waveguides offour different configurations for purposes of illustrating theversatility of applicant's invention. Waveguide 5 is a single modeoptical fiber which between face 1 and face 2 of unit 4 is embedded insolid opaque block 4 a. A significant portion of optical fiber 5protrudes from face 2 for linking, desirably by fusion at end 15 to amatching optical fiber 15 f of optical fiber system 10. The embeddedpart of optical fiber 5 has an axial cross section that has beenmodified to transition from a circular cross section at distal end 15and extending beyond face 2 into block 4 a to a rectangular crosssection at the proximal end of fiber 5 at port 11. Each of thetransitional optical waveguides 5, 6, 9 and 8 has a proximal end atleast near face surface region 1. In an exemplary embodiment of thisinvention, waveguides 5, 6, 8, 9 of interlink 4 are each a separateoptical fiber, with at least one having on its proximal end an integralhigh density filter. In another exemplary embodiment, each separatefiber 5, 6, 8 and 9 has a distal end and at least one has a high densityfilter on its distal end. Such filters are described in detail in U.S.Pat. No. 5,953,477 mentioned above. Optical fibers 5 and 6 of interlink4 protrude from face surface region 2 and each has a distal end, 15 and16, respectively, exterior to block 4 a. The longitudinal axis ofoptical fiber 6 is positioned obliquely to face surface region 1.However, high density filter 12 b on the proximal end of fiber 6 (shownmore clearly in FIG. 2) is preferably parallel to an optical fiber facesurface 1 because of the end shaping on both ends of fiber segment 6 aand on the juncture end 12 a of 6 b. It is this sort of precision andflexibility in fusing that highlights the advantages of the interlinksof the exemplary embodiments of the present invention. In anotherexemplary embodiment, the waveguides of interlink 4 are optical fiberswith the proximal end of the fibers 5 (at port 11), 6 (at port 12), 9(at port 13) and 8 (at port 14) each being slightly recessed from facesurface 1. This allows for an appropriate amount of epoxy or otheroptically transparent material for fusing the fiber ends, for example,to selected waveguide channels in planar waveguide unit 30.

FIG. 4 illustrates a cross-sectional view of an interlink comprisingcylindrical fibers with high density filters on fiber ends in accordancewith an exemplary embodiment of the invention. Referring now to FIG. 4,an interlink 41 comprises a block 44 and cylindrical fibers 45 f, 46 f,47 f, and 48 f. The block 44 is preferably constructed of a rigidmaterial opaque to the wavelengths of light expected to be transmittedthrough an embedded portion of the optical fibers 45 f, 46 f, 47 f, and48 f and light to which the unit is exposed. The optical fibers 45 f, 46f, 47 f, and 48 f provide optical channels or waveguides for carryingoptical signals. Along face surface 41 of the block 44, the opticalfibers 45 f, 46 f, 47 f, and 48 f comprise ports 45, 46, 47, and 48,respectively. Filters 45 b, 46 b, 47 b, and 48 b, typically high densityfilters, are positioned along each proximal end face of the opticalfibers 45 f, 46 f, 47 f, and 48 f, respectively, at the ports 45, 46,47, and 48 along the face 41. Distal ends 45 a, 46 a, 47 a, and 48 a ofthe optical fibers 45 f, 46 f, 47 f, and 48 f, respectively, protrudefrom a face surface 42 of the interlink 44. One or more of the distalends 45 a, 46 a, 47 a, and 48 a can include an optical filter, such as ahigh density filter 48 a positioned at the distal end 48 b. At the facesurface 42, a significant portion of each optical fiber 45, 46, 47, and48 protrudes from the block 44 for linking, preferably by fusion toanother optical fiber.

FIG. 5 illustrates a fiber of FIG. 4 having an identifier embeddedadjacent to one end of the fiber in accordance with an exemplaryembodiment of the present invention. As shown in FIG. 5, the opticalfiber 45 can comprise an outside surface 43 including an identifier 43a. The identifier 43 a is conveniently located proximate to an end ofthe optical fiber 45 where it can remain visible during operation of theinterlink 44. The identifier 43 a typically provides identificationinformation to facilitate mating of the optical fiber 45 with anotheroptical fiber or waveguide structure. The identifier 43 a preferablyincludes sufficient space for the incorporation of a micro bar code,magnetic identifier or other identification information. To assist inappropriate alignment in mating of optical assemblies, the identifier 43a can identify the dimensions and characteristics of the optical fiber45. In addition, the core and polarization axes can be identified withrespect to the location of the identifier 43 a. In the alternative,testing and alignment information can be provided by the identifier 43 ato support alignment and testing operations. It will be appreciated thatthe identifier 43 a can be positioned at other locations along theoptical fiber 45 so long as the identifier is visible to a user duringoperations of the interlink 44.

In FIG. 6, a fiber interlink 60 has tapered (oblique) proximal end faceson each of fibers 61, 62, 63, 64 and 65, which mate respectively withmating, tapered ports 61 m, 62 m, 63 m, 64 m and 65 m of a planarwaveguide 69. Similarly, a fiber interlink 66 comprises proximal endfaces on optical fibers that mate with opposing ports of the planarwaveguide 69. The interlinks 60 and 66 operate in connection with theplanar waveguide 69 to support an add-drop multiplexer application foradding and dropping optical signals of various wavelengths. Theinterlink 60 supports the drop function, whereas the interlink 66supports the add function.

For example, an optical signal input at an input port of the interlink66 is passed by an optical fiber to the planar waveguide 69. A filter atthe port 62 m passes wavelength 1 of the optical signal to the interlink60 and the remaining wavelengths of the optical signal are reflected atthe port 62 m. In turn, the fiber 61 carries the optical signal havingthe wavelength 1 through the interlink 60 to the drop application.Similarly, the filter at the port 61 m passes wavelength 2 to theoptical fiber 62 of the interlink 60 and reflects the remainingwavelengths of the optical signal. In view of the cascading nature ofthe planar waveguide 69, similar drop functions are completed at theports 63 m, 64 m, and 65 m to complete the processing of the opticalsignal the by the add-drop multiplexer.

FIG. 7 illustrates a cross-sectional view of waveguides in an interlinkin accordance with an exemplary embodiment of a present invention. Aninterlink 72 comprises waveguides 75 f, 76 f, and 77 f constructed fromoptical fibers of different configurations to provide channels forcarrying optical signals. A portion of the optical fibers or waveguides75 f, 76 f, and 77 f are embedded within an opaque block 74 comprisingmaterial opaque to the wavelengths of light expected to be transmittedthrough the embedded waveguides and light to which the interlink isexposed. Ports 75, 76, and 77 of the optical fibers 75 f, 76 f, and 77 fare positioned along a face surface 71 of the block 74. As discussed inconnection with prior embodiments, the ports 75, 76, and 77 typicallyrepresent the proximal ends of the optical fibers 75 f, 76 f, and 77 f.Optical filters can be attached to the proximal ends of the opticalfibers 75 f, 76 f, and 77 f and adjacent to the ports 75, 76, and 77.The un-embedded portion of the optical fibers 75 f, 76 f, and 77 fextend from a face surface 73 of the block 74. The distal end of eachunembedded portion of the optical fibers 75 f, 76 f, and 77 f caninclude an optical filter such as optical filters 75 a, 76 a, 77 a, and77 b.

In summary, an exemplary embodiment of the present invention provides amodified fiber interlink for linking to and providing optical channelsbetween at least one optical fiber system and at least one multi-channelplanar optical waveguide. The waveguide includes a docking surface andports optically opening on the docking surface to at least some of theoptical channels. The interlink has a first face surface for matchingthe docking surface and selected ports of the planar optical waveguide.This first face surface is configured for mating with the planar opticalwaveguide and the separate ports thereof and is positioned for opticalmatching with the selected waveguide ports. The interlink can furtherinclude a second face surface positioned in a plane at leastapproximately parallel to the first face surface. In the alternative,the second face surface can be positioned in a plane oblique to thefirst face surface.

The interlink can further include at least two modified optical fibers,each having a first fiber end that terminates near the first facesurface and is positioned at a different port of the waveguide dockingsurface. An interlink fiber can be positioned so that it is set at anoblique angle to the first face surface region. An interlink fiber canbe shaped to transition the interlink optical channel between alongitudinal length having a larger cross-sectional dimension and alongitudinal length having a smaller cross-sectional dimension. In thealternative, an interlink fiber can be shaped to transition theinterlink optical channel between a generally circular cross-section anda rectangular cross-section. One or more of the interlink fibers can beimplemented by a shaped optical fiber or by an integral high densityfilter. This integral high density filter can be positioned at one endof the interlink fiber, typically near the first face surface region.

An interlink fiber can be entirely embedded in fixed position in a rigidopaque material with only its ends exposed, as ports, one of which isfor optically mating with an optical fiber from an optical fiber system.In the alternative, an interlink fiber can be partially embedded at oneend near the first face surface region in an opaque material with theembedded end exposed as a port for mating with a port in the planaroptical waveguide. At least one of the waveguides can include anintegral high density filter positioned at one end of the waveguide.

For an alternative embodiment, a modified fiber interlink can link toand provide optical channels between at least one optical fiber systemand at least one multi-channel planar optical waveguide having at leastone docking surface and ports optically opening on the docking surfaceto at least some of the optical channels. The interlink comprises afirst face surface for matching the docking surface and selected portsof the planar optical waveguide and at least two transitional opticalwaveguides. Each of the transitional optical waveguides can comprise atleast a first transitional optical waveguide end that terminates nearthe first face surface and is positioned at a separate port in the firstface surface.

For yet another exemplary embodiment, an optical subassembly comprises amulti-channel optical planar waveguide having at least a first dockingsurface and a second docking surface. Each surface comprises portsoptically opening to waveguide channels. The optical subassembly furthercomprises two modified fiber interlinks. A modified interlink typicallycomprises a first surface with ports mating with the first dockingsurface and ports therein and a second surface with ports mating withthe second docking surface. The modified fiber interlinks can be placedin fixed relationship to the multi-channel planar optical waveguide.

In view of the foregoing, it will be appreciated that an embodiment ofthe present invention can provide an optical sub-assembly including atleast one multi-channel planar waveguide and at least one modified fiberinterlink. An exemplary optical sub-assembly can include (1) amulti-channel planar waveguide having two or more ports to at least twochannels, and (2) at least two modified fiber interlinks, each having atleast a pair of optical fibers with ports for mating with channels inthe planar waveguide. Selected channels of the multi-channel planarwaveguide can form communication channels between two modified fiberinterlinks.

An exemplary embodiment of the present invention can address the needfor precise manufacturing processes. In addition, an exemplaryembodiment also can open the door for incorporating improvements andfeatures in conjunction with waveguide-to-waveguide junctures. Anexemplary modified fiber interlink system can capture the advantages offiber shape modifications and new filter technologies without slowingthe manufacturing process of components and communications systemsbenefiting from such advances. The exemplary modified fiber interlinksystem can be incorporated as a part of high volume manufacturingoperations.

From U.S. patent application Ser. No. 09/318,451 Entitled “OpticalAssembly with High Performance Filter”

From Section of U.S. patent application Ser. No. 09/318,451 Captioned“Abstract”

Optical assembly for controlling or limiting undesirable photonentrance, reflection, departure, or appearance. A material opaque tounwanted photons can be applied to an optical assembly that wouldotherwise allow penetration of the unwanted photons. For example, afilter can be applied to a waveguide member. A first face surface of thefilter faces toward an end of the waveguide member and a second facesurface of the filter faces away from that member end. A mask adheres toone of the filter surfaces. The mask is substantially opaque in at leastsome selected spectral region to impact the extent to which photons inthat spectral region can pass through the filter and to the waveguidemember.

From Section of U.S. patent application Ser. No. 09/318,451 Captioned“Technical Field”

This invention relates generally to optical assemblies, and moreparticularly to assemblies including waveguides, for example opticalfibers, in optical connection with high performance filters.

From Section of U.S. patent application Ser. No. 09/318,451 Captioned“Background of the Invention”

Optical assemblies including waveguides in recent years have beenrecognized as offering a high potential for solving problems in a numberof commercial applications including telecommunications and medicaldiagnostics. Optical fiber assemblies are well known intelecommunications and have been found to be especially useful inanalyzing materials by employing various types of light-scatteringspectroscopy. Optical filters have been found to be useful in suchapplications. In telecommunications typical uses include bandpassfilters in wavelength-division multiplexing and as noise blockingfilters for optical amplifiers.

The term “waveguide” is used herein to refer to an optical structurehaving the ability to transmit light in a bound propagation mode along apath parallel to its axis, and to contain the energy within or adjacentto its surface. In many optical applications it is desirable to filterlight that is propagating within a waveguide, perhaps an optical fiber,in order to eliminate or redirect light of certain wavelengths or topass only light of certain wavelengths.

Many types of filters, including interference filters, are commonly usedfor this filtering. However, there are a number of difficultiesassociated with the use of many types of filters, including interferencefilters. First, in some applications the power density of lightpropagating within a waveguide may be unacceptably high for the filter,having detrimental effects that may include damage to the filtermaterial or reduced filter performance.

Also, filters are typically employed by means of bulky,multiple-optical-element assemblies inserted between waveguides, whichproduces a variety of detrimental effects. Separate optical elements canbe difficult to align in an assembly and it can be difficult to maintainthe alignment in operation as well. Each element often must beseparately mounted with great precision and the alignment maintained.Also, an increase in the number of pieces in an optical assembly tendsto reduce the robustness of the assembly; the components may be jarredout of alignment or may break. In addition, interfaces between opticalelements often result in significant signal losses and performancedeterioration, especially when an air gap is present in the interfaces.The materials of which the additional elements are composed may alsointroduce fluorescence or other undesirable optical interference intothe assembly.

The size of filtering assemblies is often a problem as well. Not onlycan it be difficult to manufacture a filter on a small surface area, butalso filtering assemblies usually contain bulky light-collimating,alignment and mounting components in addition to the filtering element.However, space is often at a premium in optical assemblies. In addition,the filtering characteristics of interference filters change dependingupon the angle at which light is incident on the filter, andinterference filters are generally designed for the filtration ofnormally incident light.

High performance filters have shown particular promise in manyapplications as described in Applicants U.S. patent application Ser. No.09/267,258 (now U.S. Pat. No. 6,222,970) and U.S. Pat. No. 5,953,477.There is an ongoing demand for assemblies in these and other industrialand medical applications that have less noise. In telecommunications thedemand for more useable bandwidth is growing at an incredible rate. Thattelecommunications demand and the recognized need for more effectivemedical and environmental diagnostic tools (for example those describedin the referenced U.S. patent application Ser. No. 08/819,979 now issuedas U.S. Pat. No. 5,953,477) are resulting in the need for assemblieshaving improved signal to noise ratio.

From Section of U.S. patent application Ser. No. 09/318,451 Captioned“Summary of the Invention”

This invention provides a surprisingly effective optical noise reductionin optical assemblies by controlling or limiting unwanted photonentrance, reflection, departure or appearance in or from the assembly.Applicants have found such unwanted photons passing through areas thathad not been recognized or had been vastly underestimated as photonpassageways potentially creating significant problems. Applicants havefurther found the optical performance loss because of these areas topresent special, technology limiting problems in applications benefitingfrom high performance filters. More specifically, applicants have foundthat penetration of unwanted photons especially in areas along peripheryof the filter layers, even very thin filter layers, can causesignificant noise or effective signal erosion. This is especially truewhen optical transmission purity/high optical performance is essential.That unwanted photon penetration occurs not only through edge surfacesbut also through face surfaces and edge junctures. The edge juncture iswhere the filter edge surface joins a filter face surface or a filterface surface joins another face, for example, of a waveguide, includingan optical fiber. Problematic optical noise can occur through the filterface itself if, for example, some areas of the filter or the waveguideto which it is optically connected have differing transmissioncharacteristics or demands. In accordance with this inventionimprovements are obtained by selectively covering with a material opaqueto the unwanted photons those areas that would otherwise allow theunwanted penetrations. Assemblies according to one embodiment of theinvention when used to cover such junctures can effectively be utilizedas universal adapters for connecting fibers to one another or to opticaldevices for specific applications, for example, in chemical analysis andor communication facilitating devices. A fiber identification mechanismassures proper fiber matching and alignment.

From Section of U.S. patent application Ser. No. 09/318,451 Captioned“Detailed Description”

A preferred embodiment of the present invention is illustrated in FIG. 8and FIG. 9. In FIG. 8 the end of an elongated waveguide, in theillustration an optical fiber 11 x, is shown having at its end mask 12x. Mask 12 x partially covers the filter end face 13 x at the end faceperiphery 14 x. Mask 12 x is opaque to at least some wavelengths oflight. Accordingly, light of the opacity wavelengths do not penetratemask 12 x thereby eliminating unwanted optical noise that would resultfrom such light penetration of the mask covered areas. Such opticalnoise is particularly problematic in applications requiring highperformance, for example, in high bandwidth telecommunications, andthose applications requiring the ability to differentiate betweenordinarily small signal differences, such as in Raman spectroscopy.Applicants' U.S. patent application Ser. No. 09/267,258 now U.S. Pat.No. 6,222,970 describes high performance filters that are an importantfactor in enabling the user to get to new performance levels. For theforeseeable future there is a conspicuous need for ever increasinglyhigher performance levels. Applicants have found the apparently extrememeasures according to this invention to enable performance levels atwhich the otherwise tolerable noise is problematic. In accordance with apreferred embodiment of the present invention high performance filterscombined with masking eliminates significant sources of unwanted lightpenetration.

U.S. patent application Ser. No. 08/819,979, now issued as U.S. Pat. No.5,953,477 referenced above describes filter performance requirements fordemanding applications, such as Raman spectroscopy. These requirementsinclude: a) high throughput in transmission wavelength region; b)high-attenuation (dense) blocking in rejection wavelength regions; c)steep transition between wavelength regions of rejection andtransmission; d) environmental stability; e) low ripple in passageregions, f) minimal sensitivity to temperature variation; g) noperformance fluctuation with ambient humidity or chemicals; h) theability to withstand high, and rapidly changing, temperatures present insterilization processes and industrial processes; i) physical toughness;and j) tenacious adhesion between filter and substrate.

These desirable filter performance properties are achieved in highperformance filters, thin-film filters having a large number ofalternating high/low refractive indices, stacked layers deposited on asubstrate. Between 20 and 150 layers are usually required depending onsuch factors as: 1) the performance required for the end use; 2) therefractive index differential between materials in adjacent filterlayers; 3) the consistency and purity of the filter layer; and 4) thesophistication of the filter design process. And, the layers must befree from defects and voids such that the material characteristics ofthe layer approaches that of a bulk solid and the packing factor of thelayer approaches 100%. Achieving high-density packing requires themolecules depositing onto the substrate to be highly energetic. Duringthe layer deposition process, this energy prevents the forming layerfrom orienting itself into columnar or similar structures that areriddled with voids. While the depositing layers are predisposed toforming the imperfect structures, the high energy forces pack themolecules (or atoms) into any voids or pinholes which may exist.

Even though the techniques described in U.S. Provisional ApplicationSer. No. 60/038,395 provide an extremely attractive means of filteringoptical fibers, the present invention provides further and nowrecognizable signal quality improvements. The present invention hasparticular advantages for instrumentation applications, such as Raman,fluorescence, and other spectroscopic analyses. They are also devisedfor wavelength division multiplexing, telecommunications, general fiberoptic sensor usage, photonic computing, photonic amplifiers, pumpblocking, fiber-integral active devices such as fiber-coupled(pigtailed) lasers and lasers utilizing the fiber as the lasing cavity.

In one embodiment of the present invention, a thin-film interferencefilter is applied to a fiber end face. The fiber core may have anessentially uniform cross section. Alternatively, the fiber, monomode ormultimode, may be up tapered so that the cross section of the core isenlarged at the filter end face and filtered light is angularlyredirected or collimated. The filter has a packing density of at least95%, but preferably greater than 99%. A fiber with an integral, maskedfilter is utilized for analytical instrumentation/sensing applicationsgenerally and spectroscopy more specifically showing improvement evenover applicants previous advanced probe systems. The coating of thefilters on the fibers can be accomplished especially effectively by amethod described in applicants U.S. patent application Ser. No.08/819,979, now issued as U.S. Pat. No. 5,953,477, discussed in moredetail below in reference to FIG. 11 and FIG. 12. The utilization ofhigh packing density filters in conjunction with up tapered fibers isdescribed in applicants U.S. patent application Ser. No. 09/280,413 nowU.S. Pat. No. 6,208,783.

As shown in FIG. 15, described in further detail below, the filter canbe applied at an angle of approximately 45 degrees such that thereflected and transmitted light can be transmitted to locations in anoptical assembly for subsequent processing. The filter can be orientedat an angle greater than the maximum angle of light propagation withinthe fiber so that reflected light from the filter cannot back propagateduring low-light spectroscopy application, such as Raman. Variabilitycan be introduced into the thin-film application process so that filtersof various wavelengths can be produced within a batch. The variabilitycan be provided by masks, intermittent blocking of the depositionparticles, off centering, and raising and lowering the substrate. Theslightly different filters can be graded and sorted.

Several short, filtered fiber segments can be aligned end-to-end withone another. One end of each fiber segment is angled and has a filterapplied to its surface. The opposite, unfiltered ends of the fibersegments may be flat or formed with mating bevels. The filters areslightly offset in wavelength from one another. The assembly can be usedto tap off signals according to wavelength or input wavelength-separatedsignals as illustrated in FIG. 14.

The preferred thin-film deposition processes impart sufficient energy tothe depositing molecules so that the forming structure is essentiallyfully packed (100% comprised of the desired molecules, essentiallynonporous, and free of voids and pinholes). For best performance, thestructure should approach or equal 100% (greater than 99%) packingdensity, but at least 95%. Due to this and other factors, adherence tothe fiber substrate is tenacious. The effects of the residual mechanicalstresses created as a result of the high energy deposition of the filtermaterial are negligible since the fiber is very strong in relation toits diameter. Several thin-film processes are particularly well suitedto produce this high-density, hard-coated filter. These processesinclude magnetron sputtering, single- and dual-beam ion sputtering, ionplating, and ion-assisted deposition (typically slightly lessperformance and lower packing densities). Reactive- and nonreactiveversions of these processes are available. The reactive processes aretypically faster in terms of the time required to produce a thin-filmcoating. These and similar processes contrast with conventionalprocesses, such as evaporative films, which achieve packing densities ofapproximately 80%. Ion-assisted deposition produces films with densitiestypically in the 95% range and for this reason are less preferable. Inshort, a filter with high packing density greater than 99%, preferablyapproaching or equaling 100%, but at least 95%—is applied directly tothe fiber end face utilizing highly energetic, non-conventionalthin-film deposition processes.

Fiber optic applications benefit from the availability of filteredfibers with slightly varied wavelengths. These applications include: 1)wavelength division multiplexing (input and output); 2) tapping offspectroscopic wavelengths for detection; and 3) matching filters tolasers with varying but closely grouped wavelengths.

In a further preferred embodiment of this invention the mask serves as asignificant component in facilitating mating with other waveguidestructures. Space 15 x is reserved for micro bar code, magnetic or otheridentification information that will assist in assuring appropriatealignment and mating of the optical assemblies. For example, the maskdimensions and characteristics could be identified. In addition thefibers core and polarization axes can be identified with respect to thelocation of the identifier and the mask aperture location, configurationand dimensions. Also, the core dimension and location can be identified.When fiber to fiber connections are made, often testing and aligning canbe a time consuming task. Proper information in the identifier spacecould minimize the testing burden. Using code in identifier space 15 xto reference specific, detailed computer link information would allowfor unlimited information about the optical assembly. The identifierinformation could be located at other locations on the mask, but thespace is desirably located where it could be used in automatingmanufacturing systems. If the optical assembly is likely to be end toend connected to another assembly in which subsequent identification isuseful, for example as illustrated in FIG. 13 and FIG. 14, an identifieron the edge can be used.

The mask of this invention is an integral part of the operable opticalassembly. Thus, it is desirable that the mask be robust and adhere tothe filter in a manner that it is not too easily removable. The maskingmaterial for the present invention can be applied in a number of waysand can be made of a variety of materials, including metals, oxides andplastics. The precise manner of forming the mask of this invention andthe material used in any given application depends on its environmentaldemands. Fluorinated plastics sold under the trademark Teflon and blackepoxy work well in many chemical applications. Durable metallic masks,for example, silver or platinum, are used in a particularly advantageousembodiment of this invention. These metallic masks can be applied using,for example, precision machining or electrolytic deposition and platingtechniques. By using photo-resist material and standard photoresisttechniques (see, for example, the descriptions for temporary maskformation in U.S. Pat. No. 5,237,630 to Hogg et al.) a temporary mask isformed in surface areas of the pre-assembly filtered fiber that are notto be covered with the durable mask. The temporary mask photoresistmaterial is applied uniformly over the entire filtered fiber endportion. The photoresist material is then exposed imagewise (todistinguish where the durable mask is and is not to be). The photoresistis removed (usually by solvent wash) from the areas where the durablemask is to be. The metallic layer is then deposited, e.g. byelectrolytic deposition, over the entire filtered fiber end portion. Asthe temporary mask is removed using a solvent wash (with a differentsolvent) any metallic deposition covering the temporary mask is alsoremoved leaving only the durable metallic mask.

Because the durable mask must withstand rigors of an operationalenvironment and adhere firmly to the substrate filter and/or fiber it isimportant in many deposition environments to assure that the substratebe thoroughly clean before applying the durable mask material. Aparticularly advantageous method for applying the durable mask usesphotoresists in another conventional manner, different from thatdescribed above. The fiber end portion is first cleaned thoroughly andthen coated over its entire surface with the durable mask material tothe desired thickness. Then a photoresist is applied over the entirearea. The photoresist in this application is chosen, imagewise exposedand developed so that after development resist remains only in the imagepattern of the desired durable mask. The durable mask material is thenremoved in the non-image areas by chemical washing or selective etching(etching only in those areas not covered by resist). The remainingphotoresist material is then removed leaving the durable mask in aprecise mask image pattern. In some applications it may be desirable torepeat the process to form multiple layers of mask having differingcompositions and/or image patterns.

The structure of a preferred embodiment of this invention is illustratedin more detail in the FIG. 9 cross sectional view in which mask 12 x isshown covering: (a) filter edge surface 22 xa; (b) the area of junctionbetween the filter and the fiber 11 x end face 22 xb; (c) the area ofjunction between the filter edge surface and the filter face 22 xc; and(d) the peripheral portion of the filter face surface 13 x distal to thefiber 22 x d. The diameter of core 21 xa is exaggerated in this view.Correspondingly the cladding 21 xb is shown as much thinner than itnormally would be. The approximate ratio of cladding thickness to corediameter in a monomodal fiber is generally about 20 to 1. Thus for a 120micron fiber the core diameter would likely not exceed 6 microns. Theoverlap 14 x of mask 12 x over distal filter face periphery is alsoexaggerated. This overlap 14 x of mask 12 x is depicted in FIG. 9 asbeing sufficiently extensive to mask light that would otherwise impingedirectly on fiber core 21 xa. Overlap 14 x could also be a minimaloverlap to extend just a short distance toward the core center coveringonly the peripheral portions of filter face 13 x and masking only lightthat would otherwise impinge on cladding 21 xb. In a preferredembodiment overlap 14 x of mask 12 x on filter face 13 x iscircumferentially uniform, defining a circular aperture to filter face13 x. In another preferred embodiment the aperture diameter is largerthan the diameter of the fiber core and exposes the entire core face.Cavity 16 x formed at its circumference by the overlap of mask 12 x andat its side proximate the fiber by filter face 13 x can be used as anesting cavity, e.g., for a sensor or an additional filters or durablemasks.

By using, for example, precision tooling, photoresist technology and/orstereo lithographic methods, the resultant masks can be of unique,complex or simple, repeatable shapes. The masks can be formed toperfectly conform to the substrate shape. The masks can also be formedto precise exterior dimensions. The mask can be formed on the fiber orcan be formed on mandrel for later application to the fiber. The filtercan be formed on the fiber before application of the mask, or the filtercan be applied with the mask. The thickness of the mask can be extremelythin and precise for some applications where, for example, only photonsof a selected wavelength are intended to pass through the mask. Thethickness can be variable, for example, when an exterior mask dimension,e.g. circumference, needs to be made to a predetermined dimensionaltolerance. Another example of where the thickness is desirably variableis when there is more than one layer in some areas of the mask, asdescribed above.

FIG. 10 is an end view of an optical assembly in which mask 32 x has across sectional configuration of a hexagon for at least some of itsaxial length. Its aperture is circular exposing filter end face 33 x.The dashed circle 32 xc illustrates the circumference of filter end face33 x and the extent of overlap 34 x of mask 32 x overlapping filter endface 33 x. The hexagonal structure is one of a wide variety of shapesthat can be chosen to accommodate coupling to other structures in a moreeasily fixed relationship. The identifier is conveniently located in acorner of the hexagonal mask 32 x where it can have additional space andremain uncovered during manufacturing operations.

In some applications, for example where space is limited, it isdesirable to form the mask as a single unit in the late stage ofmanufacturing the assembly. However, in some larger scale productionoperations, for example, the mask is desirably formed in two stages. Inthe first stage as illustrated in FIG. 11 a mask portion 42 x having acylindrical inside surface 42 xb mated to or formed around, for example,optical fiber end portion 41 x exposing fiber end face 41 xa. Theoutside surface 42 x can be of the wide variety of shapes mentionedabove for accommodating fiber coupling, with FIG. 11 illustrating ahexagonal axial external structure. Note that in this preferredembodiment identifier spaces occur on both the exterior surface 42 x andthe face surface of the first stage mask portion. The filter is thenapplied at a later stage of manufacture. The mask is also completed byadding a second stage (and any necessary additional stages) after thefilter is applied to the fiber end portion 41 xa.

FIG. 12 illustrates a further step in the manufacturing process in whicha cluster of units of the type illustrated in FIG. 11 is accumulated.Each unit includes a mask portion (with radial thickness exaggerated)surrounding a fiber. The individual units are in compact relationship toeach other. The close relationship, effectively allowing no gaps betweenmask portions, gives rise to significant manufacturing advantages.

One step necessary in applying high performance filters to fiber endfaces is to thoroughly clean and polish the fiber end faces. Applicantshave found a very effective way of accomplishing that polishing. Themethod is disclosed in Applicants U.S. patent application Ser. No.08/819,979, filed Mar. 13, 1997, now issued as U.S. Pat. No. 5,953,477,mentioned above, which is incorporated herein by reference. In brief themethod involves aggregating a large number of fiber segments in bundleswith segments parallel and in intimate relationship with the end of eachsegment that is to be coated approximately even so that the aggregateends form a roughly planar surface. The segments are firmly heldtogether and polished as a single unit to a 0.3 micron finish. Byholding the segments tightly together the amount of polishing debristhat can get between the segments is held to a minimum. After drying thebundle multilayer filter coating is applied to the polished surface ofthe aggregated fibers.

Applicants have found that even after thorough washing, small particlesof debris remain on some fibers. That debris can reduce the yield ofacceptable filtered fibers especially with the high quality demands oftoday. The debris largely gets trapped in the small spaces between thegenerally circular fibers. One way to assure that the segments are cleanis to separate the bundle and wash the fibers individually. On a smallscale that is practical. However, on a large scale separating the fibersto wash them and then bundling them again for coating is difficult andcost prohibitive. Although the FIG. 12 illustration uses only sevenfiber/mask units each having fiber end portion 51 xa encased in maskportion 52 x with identifier space 55 x, the number of such units in asingle cluster in the manufacturing process can reach into the thousandsin higher volume operations.

For reasons which will become evident below, each of the units in thispreferred embodiment has an additional identifier space on its exteriorface as illustrated in FIG. 11. Using the mask portions in the FIG. 12illustration eliminates spaces between units. By using a bundlingmaterial that holds the mask portions compactly together and surroundsthe bundle intimately, there is literally no space for debris toaccumulate. In this preferred embodiment one or more locator means(e.g., bar code information) would also be fixed to or on the bundlingmaterial for holding the units together. The bundling material, forexample Teflon tubing (Teflon is a DuPont trade name for apolyfluorinated hydrocarbon material) is then heat shrunk to hold themask portions together tightly. The fiber end of the bundle is firstscanned for digitization to, for example, record details from theidentifier spaces as well as getting configurations of each of thefibers and their associated masks. (Fibers do not all have identicalfaces.) The fiber ends with mask material is polished to a 0.3 micronfinish, the surface washed thoroughly and dried. The surface is againscanned thereby registering changes, for example, to fiber facedimensions. This second scanning is frequently useful but isparticularly appropriate when beveled end faces are created in thepolishing operation. (See FIG. 15 and U.S. application Ser. No.08/819,979, filed Mar. 13, 1997, now issued as U.S. Pat. No. 5,953,477,mentioned above.) Depending on the assembly requirements, the filter isthen applied directly to the entire surface (mask material and fiber).The peripheral extremity of the filter on each unit is then removed by,for example, using photoresist and selective etching. A surface maskportion (the second stage mask portion) can then be applied also using,for example, the photoresist methods described above.

The second stage durable mask in one preferred embodiment covers all ofthe filter edges and any selected portions of the filter face.Additional mask layers can be added subsequently as desired withdifferent or identical patterns. In a preferred embodiment of thisinvention, the surface is first scanned, digitized and information aboutthe individual fibers is recorded as indicated above. The filter is thendeposited on the entire surface in the manner consistent with that setforth in applicants copending U.S. patent application Ser. No.09/267,258, filed Mar. 13, 1999 identified above and incorporated hereinby reference. Then a first photoresist is applied, imagewise exposed,and developed to expose those areas where filter material is to beremoved (for example, the remaining resist covers entire fiber surface51 xa of unit 50 x and areas corresponding thereto on each of the maskmaterial-fiber units 50 xa-xf). The filter material is then etched offas indicated above. The surface is again thoroughly cleaned. A surfacemask portion is then applied. The remaining photoresist material is thenremoved leaving a surface of durable mask material and filter coveringthe fiber surface. Additional layers and/or patterns of durable maskmaterial is applied depending on the specific intended use of theoptical assembly.

FIG. 13 illustrates optical assembly 60 x and 60 xa with the end of mask62 x of assembly 60 x near the end of mask 62 xa of assembly 60 xa readyfor end to end connection. A further advantage of applicants robust maskis that it can be used in end to end connections for waveguides. In FIG.13 metallic mask 62 x is aligned with 62 xa such that the aperture tofilter 63 x defined by overlap 64 x mates with the correspondingaperture defined overlap 64 xa (hidden from view by perspective). It isimportant in many applications to align fiber 61 x with fiber 61 xa toachieve maximum effectiveness. This alignment can be accomplished byusing test equipment which sends light through the fibers. One fiber isrotated to achieve the correct result. Using information provided onidentifier spaces 65 x and 65 xa (in combination to reference sourcesthat may be stated therein) the alignment is accomplished without suchon site testing. Optional control port 66 x is discussed with referenceto FIG. 14 below.

FIG. 14 illustrates assembly 60 x's mask 62 x end to assembly 60 ax'smask 62 ax end relationship. After aligning fibers 61 x and 61 xa mask62 x and 62 xa the two are welded together by applying an electric fieldto the juncture seam 67 x. When connecting optical fibers end to end itis not uncommon for the weld to be a point of weakness for the fiber,especially when a filter is incorporated at the weld. By usingapplicants mask overlap as for the weld the juncture can be very strong,limited only by the specific amounts and materials used. That joint canalso provide a point for connecting other components using for example,metal solders, or for controlling the electric or magnetic field insidethe cavity formed by the mask overlap. That cavity can be constructivelyused, for example, by encapsulating a material that enhances opticalperformance or a wafer that may function as an amplifier, a sensor orsome other useful device. Using the masks of this invention to connectfibers also decreases unwanted cross talk between fibers while makingavailable sites for wanted communication between fibers. Optionalcontrol port 66 allows for inserting, for example, materials for fillingthe cavity as described above or a control light or tap into the cavity.

FIG. 15 illustrates two optical assemblies 80 x and 80 xa having matingbeveled end faces in mating orientation. In this case prior to bevelingthe fibers would be aligned. The bevel thereafter generally defines themating orientation. Core 81 x and 81 xa align and claddings 81 xc and 81xd align. When optical assemblies 80 x and 80 xa are brought togetheroverlap 84 x of mask 82 x will meet with overlap 84 xa of mask 82 xa.Fusion of overlap 84 x with overlap 84 xa will result in a cavity formedat its peripheral edge by overlaps 84 x and 48 xa and at its sides byfilter end faces 83 x and 83 xa with its volume defined by the sum ofcavities 86 x and 86 xa.

In the FIG. 15 structure and in the structure illustrated in FIG. 13 andFIG. 14 the cavity optical length dimension is controlled by thethickness of the combined mask overlap thickness. This provides betweenthe two filters (if each assembly has a filter) a resonant cavity ofshort, precise dimension. Various materials, for example, non-linearmaterials, polarizing structures, or light sensitive crystals, can beplaced between the filters to optimize the cavity for particularpurposes. Calcite provides a material base for one such polarizingstructure; another polarizing material is commercially available fromCorning Incorporated marketed under the trade name Polarcor. Thepolarizing function reduces a filter's spectral deviation to angle ofincidence variation. FIG. 16 illustrates yet another advantage of themasks of this invention. To the extent one desires an optical pathlength longer than would be provided conveniently in the FIG. 14 andFIG. 15 illustrations, in FIG. 16 the masks 91 x and 91 xa of opticalassemblies 90 x and 90 xa respectively in another preferred embodimentof this invention are tailored to fit conveniently into cylindricalconnector 98 x. Overlap 94 x and overlap 94 xa are inserted intoconnector 98 x to butt with spacer 97 x of connector 98 x. The length ofspacer cylinder 97 x is chosen so that the sum of the length of spacercylinder 97 x plus the cavity length resulting from overlap 94 x and 94xa (the resulting distance from filter 93 x to filter 93 xa) is thedesired resonant cavity length. Optional port 96 x provides theopportunity for loading the resonant cavity with material or usefulcomponents as described with reference to FIG. 14 above. Assemblies 90 xand 90 xa are secured to connector using, for example suitable adhesivesor locking methods such as those mentioned below.

A further advantage of applicants mask is the ease with which the maskslend themselves to standardization. Thus the mask exterior dimensionsare standardized to mate with the interior of a standardized connectorconfiguration. FIG. 17 illustrates another example of such a standardconnector 108 x. Optical assemblies 100 x and 100 xa are inserted intoconnector 108 x to the point where overlap 104 x meets 104 xa at theregion where port 106 x extends through the wall of connector 108 x.This illustrates a further use of port 106 x as an evacuation port toassure intimate contact of overlaps 104 x and 104 xa. Of course the portcould also be used as described above. FIG. 18 illustrates a furtherenhancement of the connector showing in FIG. 18 a an end view ofconnector 108 x of FIG. 17. Connector 108 x has been modified in theFIG. 18 illustration to include an alignment channel 111 x. Channel 111x is illustrated in more detail in blow up in FIG. 18 b. The channelalso provides a locking mechanism by including a turn in the channel.Masks 100 x and 100 xa also are modified to adapt to the FIG. 18connector by including a nub on the periphery of each of mask 100 x and100 xa sized to mate with channel 111 x. The length of the nub is sizedto accommodate the channel direction turn in the locking mechanism.

As illustrated above the masks of this invention provide a convenientand effective system for manufacturing optical assemblies for highperformance. The system includes a first unit with an optical fiber endconnected to a high performance filter. The filter/fiber end iscircumscribed by a mask that adheres to the fiber and has externaldimensions and configuration that are readily reproducible. The maskpreferably has a surface that protrudes onto the face of the filter,thus keeping unwanted photons from passing through edge and surfacejuncture areas and creating noise to an ultimate signal. The externaldimensions of the mask mate with an appropriately configured femaleconnection means. The connection means can be double ended for furtherconnection to another fiber with a mask like that on the first unit. Theconnection means could also be configured to connect to another devicesuch as a spectrophotometer. By providing a mask on the high performancefilter end that has standard external dimensions and a connecting meansmatable with the mask the ultimate assembly of final product in highvolume/high speed operations is simplified.

The present invention has been described in relation to particularembodiments that are intended in all respects to illustrate and notrestrict. Other embodiments will become apparent to those skilled in theart to which the invention pertains without departing from theinventions spirit and scope. Accordingly, the scope of this invention isdefined by the appended claims rather than the above description.

From U.S. Patent Application 60/213,983 Entitled “Micro IdentifierSystem and Components for Optical Assemblies”

This invention relates to facilitating automation of high qualityoptical assemblies in which waveguides are included and to methods forimproving quality assurance and repair of such assemblies. Suchassemblies have been found to be especially useful, for example, intelecommunications and in medical diagnostics, in pharmaceuticalresearch and chemical process monitoring. Ultra high performancewaveguides (including optical fibers), for example, associated with highperformance filters and precision micro optics are now being recognizedas having the potential to fill a critical role in the ever increasingdemand for increased bandwidth in telecommunications and to play asignificant part in providing major improvements in medical diagnosticsand pharmaceutical applications. Waveguides described herein are thoseused in propagating light typically in the 700-2000 nm range.

The invention further relates to a system having an identifyingmechanism on or in high performance waveguides that is machine-readable(especially, by optical means, for example using a laser interferencepattern) for quick and accurate recall of information included in theidentifying mechanism. Many of the individual components of such opticalassemblies are extremely small and technically complex. Differencesbetween component assembly pieces or even differences within individualpieces are difficult to discern. Although the identifier in accordancewith the present invention could be designed to serve a functional rolein the operation or use of the waveguide, the identifier is distinctfrom the traditional functional aspects of the waveguide. The identifieravoids the need for detailed reanalysis of at least one specificwaveguide technical characteristic included in the identifier. Theidentifier in some applications can be a simple mark that indicates theorientation needed in the assembly. For other applications it may bedesirable to incorporate a substantial amount of information.

The etching or engraving, for example, of a cladding surface can provideprecise and detailed product information, including: the manufacturer,the core and cladding dimensions, compositions, indices of refraction,any other imprinting that has been included, etc. In other casesadditional details may be important. As indicated in Visionex patentapplication Ser. No. 08/819,979 filed Mar. 13, 1997, entitled “Methodand Apparatus for Improved Fiber Optic Light Management,” now U.S. Pat.No. 5,953,477, the optics associated with individual waveguides can havespecial characteristics. For example, the end face of one fiber may beintentionally angled so that its face is not uniformly perpendicular toits axis and the axis of a waveguide with which it is to be mated. Itmay be a very slight angle and it may be critical to have the end faceprecisely oriented as it mates with the waveguide. The identifier on thefiber and the waveguide provide sufficient information for the mating tobe precise. One advantage of using the peripheral surface of a fiber endface is the relative space availability. The entire periphery could beutilized if information need and image clarity required. Similarly, theprobability of that area causing fiber function limitations is low andcould be reduced further, for example, by covering disrupted(etched/engraved) surface areas with material that would restoretransparency to wavelengths negatively affected without detrimentallyaffecting the readability of the image. Such factors play a role indetermining which identifier process, marking and location to utilize.

It also may be critical to high volume production for the information tobe read significantly in advance of the mating operation and in somecases even by a different manufacturer. In one embodiment of theinvention the automated system, for example, uses pre-aligned/orientedfiber segments locked into position by a belt or cartridge. The belt orcartridge is fed at the mating location for placement of fiber segmentsin predetermined alignment/orientation. (see FIG. 20 a.) Thismanufacturing flow allows operations to be maintained at a rate that isnot limited by the alignment function. It also allows for efficient taskseparations. In many cases it is desirable for each fiber segment end tohave its own identifier. With longer segments it is advantageous toinclude some of the information at intervals along the segment. In suchcases that the interval identifier would include distinguishingcharacteristic(s) to avoid confusion with end face identifications. Thechoice of location of and type of identifier depends on the specificapplication as indicated below. In some cases it may be desirable tohave identical identifier markings in more than one location. Forexample, in assemblies in which there will be face-to-face connection oftwo optical fiber segments, it may be desirable to include theidentifiers on both the face periphery and the fiber wall periphery nearthe edge. The fiber wall peripheral markings would be readable evenafter face-to-face connection. This would be beneficial for both repairand quality assurance.

Several embodiments of the identifier means are illustrated in FIG. 19in which fiber 11 y has a core 11 ya and cladding 11 yb. Fiber end face13 y, which could include an integral filter has included in itsperipheral area (near edge 17 y which is the junction of end face 13 yand fiber wall 19 y) identifier space 15 ya. Identifier 15 ya can besimply a registration mark or can include more detailed informationabout the fiber. End face 13 y also includes in its peripheral areaoptional or alternative registration marks 15 yc that can be used inassuring, for example, proper rotation of fiber 11 y in an assemblyoperation. It is preferable to locate the identifier in the claddingarea that is not in the substantive evanescent field of propagatinglight, i.e. outside the mode field diameter. In a preferred embodimentthe identifier is in spaces in the cladding periphery, at least in aboutthe exterior 80 percent, advantageously in the exterior 50 percent,especially in the exterior 20% and, in some cases, ideally in theexterior 10% to avoid interfering with the photon transmission purposesof the waveguide segment. Fiber wall 19 y includes identifier space 15yb which can contain the same information as space 15 ya or couldcontain different information.

As shown in perspective view in FIG. 20, the system also includesreading means 22 ya, 22 yb, and 22 yc for sufficient identification toinitiate appropriate reaction. Advantageously the system includes meansfor reacting to the identifier information, process 24 y, and desirablymeans, drive motor 23 yc, for appropriate adjustment of the placement ofthe waveguide, for example in mating with another waveguide. Thus, forexample, as illustrated in FIG. 20 a waveguide (fiber segment 21 y)rests on a pair of precision rollers 26 y at least one of which ismounted for controlled rotation by drive motor 23 yc. Drive motor 23 ycis mounted on circular platform 28 y, which rotates in synchronizedmovement with assembly belt 29 y. As fiber segment 21 y passes in theview area of camera 22 yc, information from its identifier is read andpassed on to processor 24 y. Processor 24 y digests the identifierinformation and compares it with information as to, for example, thedisposition of the segment about its axis. Segment 21 y is needed to berotated axially for perfect alignment with its mating assembly member 25y. Information is then communicated from the processor to drive motor 23yc to rotate the fiber by rotating the roller(s) 26 y. Cameras 22 yb and22 ya communicate through the processor with drive motors 23 yb and 23ya respectively. Drive motor 23 yb is geared finer than 23 yc for moreprecise adjustment of fiber segment 21 y, which motor 23 ya is gearedeven finer than motor 23 y to assure precise alignment. After fibersegment 21 y is joined in precise alignment with piece 25 y by, forexample, fusing the fused pieces picked off for subsequent inspection,use, distribution, etc. FIG. 20 a illustrates in end view cutaway drive23 ya having rollers 26 ya supporting fiber segment 21 ya. By drivingone or both rollers 26 ya, drive 23 ya effectively adjusts the rotationof fiber segment 21 ya.

If both the mating members in mating assemblies have identificationinformation on their respective peripheral areas the match could beidealized by appropriate to the information. Waveguides having suchidentification in one or more locations as substantially permanentidentification for the fiber segment another aspect of this invention.The use of the cladding, especially the cladding peripheral areas, asthe location of the identifier information is an especially preferredembodiment of this invention. The use of such identifier for qualityassurance is another preferred embodiment of the invention.

The identifier can be placed on each piece in a number of different wayson one or more surfaces of the waveguide. FIG. 21 illustrates inperspective view several options for placement or configuration ofidentifier spaces. Fiber 31 y with core 31 ya and cladding 31 yb has onits end face 33 y identifier spaces 35 ya and 35 yc. In this embodimentdifferent information is included in space 35 ya from that included inspace 35 yc. The information in space 35 ya could be, for example, codedinformation relating to the technology in the fiber, while the codedinformation in space 35 yc could identify the manufacturer, plantlocation, manufacturing line, specific run, etc. Information identicalto that included in 35 ya and 35 yc is included in spaces 35 yb and 35ye respectively which are located on fiber wall 39 y. The location ofidentifier space on the fiber side wall permits continuingidentification after the segment is joined at its end face to anotherassembly piece. Information space 35 yd is included to illustrate that aplurality of identifier spaces can be utilized when appropriate.

Identifier information can actually be imprinted in the cladding of anoptical fiber, for example, by a technique similar to those used forfiber-Bragg gratings. Such gratings are normally applied to Ge-dopedfiber core material as disclosed in U.S. Pat. Nos. 4,807,950 (950) and4,725,110 (110). U.S. Pat. No. 5,235,639 discloses a method for“writing” an in line grating with high-silica glass. Although thattechnique could be rather expensive it does have some appeal. FIG. 22illustrates fiber 41 y having a core 41 ya and cladding 41 yb. Althoughfiber 41 y has an identifier space 45 y and information thereon, it alsohas a series of precisely located disruptions 48 y in the index ofrefraction of peripheral cladding interior. These disruptions 48 y areinduced in a manner generally consistent with the disclosure, forexample, in the above referenced 950 and 110 patents as modified in the'639 patent. However, instead of focusing the actinic radiation in thefiber core the radiation is focused in the cladding. Using the claddingto locate an information repository is another important embodiment ofthis invention. It is preferable to locate the disruptions in thecladding periphery, at least in about the exterior 80 percent, desirablyin the exterior 50 percent, especially in the exterior 20% andpreferably in the exterior 10% to avoid interfering with the photontransmission purposes of the waveguide segment.

FIG. 23 further illustrates purposefully created index of refractiondisruptions 58 y in cladding 51 yb of fiber 51 y having core 51 ya.Since such disruptions can be crafted to be wavelength specific, a largenumber of individual wavelengths translated into codes are readilyreadable. As with the case of the surface identification spaces, forexample in FIG. 21, these sets of disruptions can be placed in differentlocations around the fiber periphery with each set, e.g., having adifferent wavelength selectivity. Thus, it would be possible tostandardize a given wavelength or combinations of wavelengths as codesrepresenting, e.g., specific fiber runs and/or product codes.

In a recent Visionex patent application entitled “Optical Assembly withHigh Performance Filter,” filed May 25, 1999, (assigned U.S. Ser. No.09/318,451) we disclosed but did not claim another aspect of thisinvention. That aspect is “identifier space 15” as disclosed in thefollowing, a quote from the paragraph transcending pages 8 and 9 of thatapplication:

“In a further preferred embodiment of this invention the mask serves asa significant component in facilitating mating with other waveguidestructures. Space 15 is reserved for micro bar code, magnetic or otheridentification information that will assist in assuring appropriatealignment and mating of the optical assemblies. For example, the maskdimensions and characteristics could be identified. In addition thefiber's core and polarization axes can be identified with respect to thelocation of the identifier and the mask aperture location, configurationand dimensions. Also, the core dimension and location can be identified.When fiber to fiber connections are made, often testing and aligning canbe a time consuming task. Proper information in the identifier spacecould minimize the testing burden. Using code in identifier space 15 toreference specific, detailed computer link information would allow forunlimited information about the optical assembly. The identifierinformation could be located at other locations on the mask, but thespace is desirably located where it could be used in automatingmanufacturing systems. If the optical assembly is likely to be end toend connected to another assembly in which subsequent identification isuseful, for example as illustrated in FIG. 6 and FIG. 7, an identifieron the edge can be used.” (See FIG. 13 and FIG. 14 as attached hereto.)

The drawings in that application show several examples of suchidentifier spaces (FIG. 1, 15; FIG. 3, 35; FIG. 4, 45; FIG. 5, 55; andFIGS. 6, 65 and 65 a—see FIG. 8, 15 x; FIG. 10, 35 x; FIG. 11, 45 x;FIG. 12, 55 x; and FIGS. 13, 65 x and 65 xa, as attached hereto).

Additionally language of the May 25, 1999 patent application mentionedabove has relevance to describe how identification would be applied to,for example, peripheral areas of the fiber. See page 9 beginning in line17: “By using photo-resist material and standard photoresist techniques(see, for example, the descriptions for temporary mask formation in U.S.Pat. No. 5,237,630 by Hogg et al.) a temporary mask is formed in surfaceareas of the preassembly filtered fiber . . . . The temporary maskphotoresist material is applied uniformly over the entire filtered fiberend portion. The photoresist material is then exposed imagewise . . . .”

(The following is new information but continues the thought) . . . toprovide the identifier information. The photoresist is removed (usuallyby solvent wash) from the appropriate surface in an image wise patternof the identifier information. The identifier information is thenprovided, for example, to the surface, e.g. by etching, or electrolyticdeposition. In the latter case, as the temporary mask is removed using asolvent wash (with a different solvent) any metallic deposition coveringthe temporary mask is also removed leaving only the durable metallicidentifier information in a precise identifier image pattern. Becausethe identifier information must be precise and be robust it isimportant, especially in many deposition environments, to assure thatthe substrate filter/or fiber be thoroughly clean before applying maskmaterial and identifier. For some applications, a preferred embodimentincludes the creation of the identifier by using precision laseretching/engraving techniques.

In a preferred embodiment a narrow view would include:

A fiber optic segment having an end face, a peripheral end face surfaceand peripheral edge surface said segment including at least one machinereadable identifier which is readable from at least one of saidperipheral surfaces.

A broader view would include:

A waveguide including at least one machine readable identifier.

1. A method comprising: providing a fiber segment, operable to guidelight longitudinally, comprising: a first end face; a second end face; acylindrical surface extending lengthwise from the first end face to thesecond end face; and a volume defined by the first end face, the secondend face, and the cylindrical surface, the volume comprising a series ofdisruptions in index of refraction; generating a laser interferencepattern from the series of disruptions in index of refraction; readingthe laser interference pattern through the cylindrical surface with acamera; and determining a code based on the read laser interferencepattern.
 2. A method comprising: providing a segment of optical fibercomprising a first end face, a second end face, and a cylindricalsurface extending from the first end face to the second end face;forming refractive index disruptions within a volume defined by thefirst end face, the second end face, and the cylindrical surface inresponse to illuminating the segment of optical fiber with actinicradiation; generating a laser interference pattern from the formedrefractive index disruptions; reading the laser interference patternthrough the cylindrical surface with a camera; and determining a codebased on the read laser interference pattern, wherein the volumecomprises a core that extends between the first end face and the secondend face and that is circumferentially surrounded by a cladding area,with the refractive index disruptions located in the cladding areaoutside a mode field diameter of the core.
 3. A method comprising:providing a segment comprising: a first face at a first end of thesegment; a second face at a second end of the segment; an outercylindrical surface extending from the first face to the second face; acylindrical volume defined by the first face, the second face, and theouter cylindrical surface, the cylindrical volume comprising: acylindrically shaped region disposed axially in the cylindrical volumeand extending lengthwise between the first face and the second face; asecond region disposed circumferentially about the cylindrically shapedregion, extending laterally from the cylindrically shaped region to theouter cylindrical surface, and extending lengthwise from the first faceto the second face; and silica doped to provide a refractive indexdifferential between the cylindrically shaped region and the secondregion, the refractive index differential forming a totally internallyreflective interface; and providing refractive index disruptions withinthe cylindrical volume, the refractive index disruptions created byilluminating the segment with actinic radiation; generating a laserinterference pattern from the refractive index disruptions; reading thelaser interference pattern through the outer cylindrical surface with acamera; and determining a code based on the read laser interferencepattern.